Manufacture of alloy steel



' UNITED STATES "PATENTQOFFICE.

ROBERT ABBOTT HADFIELD, 0 F WESTMINSTER, ENGLAND.

HANUFACTURE OF ALLOY STEEL.

He Drawing.-

To all whomtt concern Be it known that I Sir ROBERT Anson llanrninu, Baronet, F. S., a subject of the King of Great Britain and Ireland, residing at the 'cit vof Westminster, England, have invented mp-rovements-in or Relatmg to the Manufacture of Alloy Steel, of which the following is a s ecification.

An advantage 0' using nickel or chr0- Znium, or nickel and chromium, in the manu 'facture of alloy steels is that the steel is rendered more sensitive to hardening, which, when followed by tempering, enables thicker masses of such steel to be hardened and tempered in a better manner than carbon steel can be hardened and tempered. For example, if a heated mass of carbon steel, say three inches in thickness, be quenched in a cooling medium and then tempered, the firsthardening produced byguenchin does not penetrate Very deeply, consequent y the grain of the steel obtained is not properly changed and the subsequent tempering of the steel produces little or no improvement istics, amon such hardened steel in the construction of aerop this respect, When nickel or chromium, or nickel and chromium, is or are used in the manufacture of steel, the hardening pone trates much more deeply, consequently when is afterward tempered, the mateiialis much stiiiferquality. blow l have discovered as the result of experiments, that the presence of manganese between predetermined percenta e limits, in

tions, be used in lieu of thesemuch more ear pensive metals, to produce an alloy steel capable of being hardened and temperedin an advantageous manner to oroduce mate rial possessing Valuable technical characterwhich may be mentioned its power of o -ering considerable resistance to tensile and shock'stresses, such as is ofi'ered by nickel steel, chromium steel, and nickel chromium steel, and which can therefore be used in lieu of these expensive steels for yarious practical purposes as for instance lanes, motor cars, for 'instanoe crank shafts, and so forth where the material isliable to be subjected to considerable tensile and shockstresses.

I have found that a manganese alloy steel,

.such as referred to, possessing 'valuable characteristics such as those mentioned, can be obtained when made wlth from about one quenching them, as

- temperature of from about 450 in water,

Specification of Letters Patent. Patented D c, 21, 1920 Application filed May 24,1920. Serial m. 883,914.

decimal four to three and a half per cent.

of manganese andvwith carbon and silicon com aratively low, and when subjected to a sultable heat treatment. Thus, good results have been obtained with alloy steels According to one example, satisfactory re sults have been obtained with alloy steels containing in addition to iron, from about .23 to .29% say .3% of carbon, from about .22 to 27% say 3% of silicon and about 1.39% say 1.4:% of manganese, sulfur and phosphorus being low, such steels being heat treated by beating them to a temperature of the order of about 800 to 900 (1, advantageously about 850 3., then rapidly cooling them, as by quenching them in water, or oil, then reheating them to a temperature of the order of from about 600 to 700 C, advantageously about 650 6., and then again in water or oil.

The steel in some cases be reheated, preparatory to the second quenching, to a up to sayebout 700 6]., instead of from about 600 to'700 (3., according-to the physical qualities desired and the percentages of carbon and manganese present, and quenched in oil or water, or allowed to cool in the air, if the quenching of thealloy steel is efiected the temperature of the steel preparatory to the first quenching may be 20 to 40 lower than when quenching in oil.

In the case for example of small bars of alloy steel of about one and one eighth inches thickness and containing fiom about 1.4% up to about/2% manganese, satisfactory results have been attained by introducing the bars into a furnace at a temperature of about 850 C. and allowing them to soak at this temperature for about half an hour,

then removing them from the furnace and,

ing them in water. I

somewhat. As a specific quenched in water for a period of about one and a quarter minutes, then reheated to about 850 C. and again quenched. The mecontaining say 3% chanical test obtained from the crank shaft thus treated was as follows :-elastic limit, 34 tons; yield point, 37 tons; breaking load, 55 tons; elongation, 2d%; reduction of area,

. 55%; izod test, ft. lbs. 30, angle, 7.

For an alloy steel of the kind referred to of manganese, the carbon may advantageously be below .5% and it may be down to 2%. Steel thus constituted, after being heat treated as described, and advantageously by heating it to about 800 (1.,

and quenching it in oil and then reheating it to. about 650 C. and quenching it in water,

yields a material of great commercial value.

Thus, in one example an alloy steel having the following composition: C, .33; Si, .30; Mn, 3.21 when heat treated as just described yielded the following test, namely: elastic limit, 48 tons; yield point, 52 tons; breaking load, 60 tons; elongation, 18%; reduction of area, 40%. r

lf with about 3% of manganese the carbon be above about 50%, the brittleness of the alloy steel is very marked and the steel would probably not be of much commercial value for purposes such as herein indicated, while (30111111616131 value for such purposes on account of its greater softness.

and chromium,

elements may Alloy steel of the kind may be produced by refining in an electric furnace, a normally finished carbon steel produced in an open hearth furnace, or by any other suitable process, centage of manganese being insured by addition, ifneed be, of manganese in the form, for example, of ferro-manganese at any suitable stage in the manufacture of such stee Alloy steels accordingto the invention, may, in some cases, .and for enhancing the qualities thereof for special purposes, include one or more additional metals, for instance nickel, or chromium, or both nickel but usually in such cases'the such additional element or be small, say of the order of up to about 1% (one per cent.) of eich, or taken togetherf-As such element or elements facilitate the hardening of the alloy heated, and subseit or they is proportion of hardening temperature of about 855 G., it was then herein described the desired peror are included in the term hardening metal used in some of the appended claims.

this invention the percentage of carbon may example to about .4 to .6% if the manganese be reduced to below say about 2% and down to about one decimal four per cent.

What ll claim is 1. An iron manganese alloy steel containing from about decimal two to decimal'six of one per cent. of carbon and from about one decimal four to about three decimal five per cent. of manganese.

2. An iron manganese alloy steel containing from about decimal two to decimal six of one per cent. of carbon and from about one decimal four to about three decimal five per cent. of manganese, silicon not exceeding about decimal three of one er cent.

3. An iron manganese al oy steel containing from about decimal two to decimal six of one per cent. one decimal four to about three decimal five per cent. of manganese, the higher the percentage'of manganese the lower being the percentage of carbon, silicon, sulfur and phosphorus being low as set forth.

4. An iron manganese alloy steel contain-' of carbon and from about ing from about decimal two to decimal' three of one per cent. of carbon and from about one decimal four per cent. to about.

silicon and from about one decimal four to" about two per cent. of manganese.

if the carbon be below about 2% the resulting material would probably not be of much 6. An iron manganese alloy steel ing from about decimal two to decimal six of one per cent. of carbon and about one decimal four per cent. of manganese.

7 An iron manganese alloy steel containing about decimal three of one per cent, each of carbon and silicon and about one decimal four per cent. of manganese.

8. 11 iron manganese alloy steel containing from about decimal two to decimal six per cent. of carbon from about one decimal four to three decimal five per cent. of manganese and a hardening metal as set forth.

9. An iron manganese alloy steel containing from about decimal 'two to decimal six percent. of carbon, four to three decimal five percent. of manganese and a hardening metal as set forth up to about. one per cent. I

10. An iron manganese alloy steel capable of ofi'ering' considerable resistance to tensile and shock stresses, such as is ofiered by nickel steel chromium steel or nickel chro mium steel and containingiron with from about debimal two to decimal six of one per cent. of carbon and from about one decimal four to three'decimal five per cent. of mancontairifrom about one decimal ganese and treated by heat to a relatively high temperature, then rapidly cooled, then reheated to a lower temperature and again cooled.

11. An iron manganese alloy steel capable of offering considerable resistance to tensile and shock stresses such as is offered by ,nickel steel chromium steel or nickel chr0- of offering considerable resistance to tensile and shock stresses, such as is offered bynickel steel, chromium steel or nickel chromium steel and containing iron with from about decimal two to decimal six of one per cent. of carbon and from about one decimal four to three decimal five per cent. of manganese and treated by heat to a temperature of from about 800 to 900 C., then rapidly cooled, then reheated to from about 450 to 700 C. and again cooled.

13. An iron manganese alloy steel capable of offering considerable resistance to tensile and shock stresses such as is offered by nickel steel, chromium steel and nickel chromium steel, containing iron with from about decimal two to decimal five of one per cent.

of carbon and from about one decimal four to about two per cent. of manganese and treated by heat to a temperature of'from about 800 to 900 C. then rapidly cooled, then reheated to a temperature of from about 450 to 700 C. and then again cooled.

14. An iron manganese alloy steel capable of offering considerable resistance to tensile and shock stresses such as is offered by nickel steel, chromium steel and nickel chromium steel, containing iron with from about decimal two to decimal five of one per cent. of carbon and from about one decimal four to about two per cent. of manganese and treated by heat to a temperature of from about 800 to 900 C. then rapidly cooled, then reheated to a tem erature of from about 450 to about 600 and then again rapidly cooled. p

15. As a new article of manufacture, an iron manganese steel alloy low in silicon,

sulfur and phosphorus as set forth, contai'ning from about decimal two to decimal six per cent. of carbon and from about one decimal four to three decimal five per cent. of manganese and capable of offering considerable resistance to tensile and shock stresses such as is ofiered by nickel steel, chromium steel and nickel chromium steel to such stresses.

Signed at London in the county of London, England this twenty ninth day of April 1920.

ROBERT ABBOTT HADFIELD. 

